Base Mainnet will be going through a hard fork. This hard fork is special because op-geth has been deprecated and we will move to op-reth.

The StreamingFast team has instrumented op-reth for full Extended Blocks support. op-reth will introduce the v5 block format which has a few changes. (see the firehose release notes for details).

op-reth with v5 blocks has already been rolled out on Base Sepolia Testnet should you wish to test ahead of the Mainnet rollout.

An update will be provided after we switch to the v5 block format.